TIM3, also known as HAVCR2, is a member of the recently discovered T cell Ig and mucin domain-containing molecule superfamily. TIM3 is a negative regulatory molecule that is important for T cell tolerance and has a crucial role in autoimmunity and T cell exhaustion during chronic viral infection (PMID: 23180819). TIM3 is expressed by T-helper type 1 (Th1) cells, macrophage, monocyte, dendritic cells, CD8+ T cell and other lymphocyte subsets. Galectin-9 is a ligand for TIM3. TIM3-galectin-9 pathway negatively regulates T helper type 1 immunity (PMID: 16286920). TIM3 is a 280-aa membrane protein with a calculated molecular weight of 33 kDa, the higher molecular weights between 50 and 70 kDa detected by this monoclonal antibody probably represent glycosylated TIM3 (PMID: 20107545; 17069754; 11725301).